@article{ref1,
title="Can a threshold for 11-nor-9-carboxy-Δ<sup>9</sup> -tetrahydrocannabinol in hair be derived when its respective concentration in blood serum indicates regular use?",
journal="Drug testing and analysis",
year="2019",
author="Zinka, B. and Epple, S. and Schick, S. and Skopp, G. and Graw, M. and Musshoff, F.",
volume="11",
number="2",
pages="325-330",
abstract="A 100 μg/L or higher concentration of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) in blood serum is generally assumed to be associated with regular and/or heavy use of cannabis. At present, determination of the extent of cannabis use by means of the concentration of THC-COOH in hair has not been assessed. Therefore, we aimed at establishing a threshold for THC-COOH concentrations in hair to prove frequent consumption by comparing THC-COOH concentrations in 129 corresponding serum and hair samples, respectively. The concentration of THC-COOH in the serum was analysed by gas chromatography/mass spectrometry and in the hair by liquid chromatography/tandem mass spectrometry. Data were statistically evaluated using receiver operating characteristic curves and contingency tables. Our results suggest that a THC-COOH concentration of ≥ 4.2 pg/mg in hair was always accompanied by a THC-COOH concentration of at least 100 μg/L in blood serum. Should this be confirmed by further studies of a larger study population, a hair concentration of 4.2 pg/mg THC-COOH can be set as a threshold to predict regular and/or heavy consumption of cannabis even if no corresponding blood sample is available for analysis.<br><br>This article is protected by copyright. All rights reserved.<p /> <p>Language: en</p>",
language="en",
issn="1942-7603",
doi="10.1002/dta.2496",
url="http://dx.doi.org/10.1002/dta.2496"
}